The objective of this project is to supply microbiologic diagnostic services of a high quality for the study of actual and potential infection of cancer patients with viruses, bacteria, mycoplasma and fungi. Further obejctives are to study the patients' normal flora, food and environment in an effort to curtail acquisition of potentially pathogenic agents and supply support for evaluation of protective environments and various research investigations. A serum bank provides sera from cancer patients for use by all investigators at the BCRC. A total of 24,340 patient samples were cultured for bacteria and/or nycoplasma and fungi during calendar year 1975. All microorganisms recovered were speciated and otherwise identified by serotyping or bacteriophage typing whenever possible. Development of resistance to commonly used antibiotics is continuously monitored. Additional studies of antibiotic susceptibilities were done with several new antibiotics and susceptibilities to 6 species of Group D streptococcus were also determined. A total of 186 samples were examined for viral isolation and 314 samples for viral antibody titers. Viral recovery rates ranged from 5 to 10 percent. Approximately 73 percent of sera had an 8-fold or greater titer rise to one or more viral antigens.